bigslim

I have a 85 GL-10 1.8 EFI 2wd 3 speed auto. The tranny just went out the other day (for the 3rd time), and I need some info about changing it. First the car is a POS that I drive to work so Im not intrested in swaping a 5 speed into it, Id just like to replace it with the same. I have found a used 3 speed for $300, is this an ok price? Also Iv been told to replace the toqure converter, why should I do this? I know about flushing the radiator so that any metal will not get into the new trans. I plan on doing it myself, so I thought Id rent a tranny jack. Any other advice, info, or links would be appreciated. Thanks